Question

Among the following oxioacids, the correct decreasing order of acid strength is
A. `HCIO_(4)gtHCIO_(3)gtHCIO_(2)gtHOCI`
B. `HCIO_(2)gtHCIO_(4)HCIO_(3)gtHOCI`
C. `HOCIgtHCIO_(2)gtHCIO_(3)gtHCIO_(4)`
D. `HCIO_(4)gtHOCIgtHCIO_(2)gtHCIO_(3)`

Answer 1

Correct Answer - A
i. Decreasing acid strength is due to the decrease in oxidation state of central atom e.g. `overset(+7)HCIO_(4) gt overset(+5)HCIO_(3) gt overset(+3)HCIO_(2) gt overset(+1)HOCI`
ii. Decreasing acid strength is also due to the decrease in number of reasonating structures of their conjugate base, e.g.
`HCIO_(4)+H_(2)O rarr H_(3)O^(o+)+CIO_(4)^(Theta)`

Other three conjugate base, e.g.,
`CIO_(3)^(Theta)` ,`CIO_(2)^(Theta)` and `CIO^(Theta)` show 3, 2 and 1 resonating structures.